When history loading is the default "ask', if I answer a non-zero number of days to the dialog that pops up on startup, the requested amount of history is properly loaded, but the last pageful of history is repeated after the line "++++ End Of History ++++", with their timestamps.
When reloading history afterwards through the Debug menu, the effect disappears.
I suspect the startup-time loading of recent history is not disabled by the dialog, and fires after the loading itself.
This is 1.477 on both Windows and Linux, and has been present for several Tkchat versions.
root (claiming to be patthoyts) added on 2016-09-27 22:20:38:
When we connect to the multi-user chat (MUC) using a Jabber client, the MUC sends a small amount of recent messages. This is what gets shown below the end of history marker. All the stuff above the marker is retrieved by web requests from the server where we maintain log files. The last portion of that is duplicated in the history. When you reload, you are not reconnecting to the chatroom so you don't get the MUC catchup stanzas - just the downloaded history.
We could add some logic to prune out the duplicates but I think it's unlikely to actually get done.